1. Field of the Invention
This invention relates to power supplies for amplifiers, and particularly to a power supply which can be biased using phantom power derived from a signal carrying line.
2. Description of Related Art
In certain audio consoles it is customary to provide d.c. power along the audio signal receiving lines to bias certain types of microphones. This power is known as "phantom" power because it is provided on the same lines as the audio signal is received. Such audio consoles are used in recording studios, commercial sound systems, PA systems, and sound reinforcement systems.
Certain types of audio instruments provide an unbalanced output. Modern audio consoles require a balanced audio input. Accordingly, it is conventional to provide a device for interfacing low or high level unbalanced lines from the audio equipment to low level balanced inputs on the consoles. These devices normally are supplied with individual power supplies which may take the form of a battery pack or the like. Such devices which use battery packs require that the batteries be changed on a frequent basis. This operation proves to be inconvenient.